#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const int mod=1e9+7;
const int N=200013;
typedef long double ld;
ll a[N];
ld b[N];
ld p[N];
int n,k;

bool chk(ld x){
    for(int i=1;i<=n;i++)b[i]=a[i]-x,p[i]=p[i-1]+b[i];
    if(p[n]<p[0])return false;
    vector<ld>v;
    for(int i=1;i<=n;i++)if(p[i]>=p[0]&&p[i]<=p[n]){
        if(v.empty()||v.back()<=p[i])v.push_back(p[i]);
        else{
            auto f=upper_bound(v.begin(),v.end(),p[i])-v.begin();
            v[f]=p[i];
        }
    }
    return v.size()>=k;;
}

void solve(){
    cin>>n>>k;
    for(int i=1;i<=n;i++)cin>>a[i];
    ld l=0,r=1000;
    for(int i=0;i<50;i++){
        ld mid=(l+r)/2;
        if(chk(mid))l=mid;else r=mid;
    }
    cout<<fixed<<setprecision(12)<<l<<'\n';
}


int main(){
    ios::sync_with_stdio(false);
    int T=1;
   // cin>>T;

    while(T--)solve();
}